In the illustrative embodiments of the invention disclosed, the piston unit of a gas spring incorporates a meander-shaped fluid passage for interconnecting the working chambers on either side of the piston unit so as to dampen movement of the piston rod relative to the cylinder. The meander-shaped passages may be constituted by a sequence of passage sections arranged at right angles to one another and, in one embodiment, are formed in the end faces of the piston member so as to lie in planes transverse to the axis of the cylinder. If desired, additional fluid passage units may be connected in series to provide an enhanced damping effect.

A device that maintains the water level of a swimming pool within acceptable limits. The device includes a valve member that has a valve chamber and a diaphragm chamber. The valve member is held in submerged relation to the water level in the pool by a weighted member that is provided with a stabilizer so that the correct position of the submerged valve member is maintained at all times. A garden hose is connected at one end to a source of water under pressure and its other end is connected to the valve chamber. One side of the diaphragm is exposed to the water in the pool and its other side is exposed to atmospheric pressure so that when the pool level changes, the change is detected by the diaphragm. An on-off valve in the valve chamber is normally closed so that a valve at the water source may be left in its open position at all times. A drop in the water level displaces the diaphragm and the displacement of the diaphragm opens the valve in the valve chamber so that water from the water source is admitted into the pool. The valve in the valve chamber closes when the water level rises to a desired level, which rise is detected by the diaphragm.

A diaphragm type of flush valve for use with toilet devices such as urinals and water closets includes a body with an inlet and an outlet and there is a valve seat therebetween and a valve member movable to a closing position on the valve seat. The valve member includes a diaphragm which is peripherally attached to the body. There is a pressure chamber above the diaphragm for holding the valve member on its valve seat and there is a filter and a bypass orifice connecting the inlet and the pressure chamber. The filter includes a filter ring positioned beneath the diaphragm and adjacent the outer periphery thereof. The filter ring and the diaphragm are held in a fixed position relative to each other. The filter ring has a plurality of outwardly directed circumferentially spaced filter grooves. There is a seal ring between the filter ring and the body and facing the grooves. A peripheral chamber is bounded by the seal ring, the filter ring and the body, with water reaching the peripheral chamber by passing through the filter ring grooves. There is an orifice connecting the peripheral chamber and the pressure chamber.

A device for dispensing water front a source of water under pressure to at least one water using attachment, includes a basin and a water dispensing adjustable diaphragm fill valve. The water using attachments may have various configurations such as but not limited to garden planters and pots, terrariums, ant farms, garden pot converters, underground springs, Christmas tree stands, animal waterers, animal waterer/feeders, bird baths, hummingbird feeders, amphibian habitats, animal cages, bird cages, pond filter/fountains, aquariums, air conditioners and water toys. The basin holds a volume of water and has a closed bottom, at least one side wall, and an open top and includes a water inlet port adapted to connect the basin to the source of water under pressure. A mounting rim is positioned adjacent to the open top for mounting the water using attachments, and a seat is provided for readily accepting and releasing the fill valve within the basin below a selected water line. The adjustable diaphragm fill valve is mounted on the seat and maintains a volume of water in the basin at a predetermined level. The fill valve has at least one water outlet port for dispensing water from the fill valve into the basin.

A fill valve for controlling liquid level in a toilet water tank or other tank includes a valve head assembly positioned at a selected level in the tank by a telescoping riser assembly with liquid inlet and outlet conduits extending toward the tank bottom. An adjusting nut on a stationary riser engages thread structures on inlet and outlet conduits for raising or lowering the valve head assembly and adjusting the liquid level. A main valve in the head assembly is controlled by a non-horizontal diaphragm separating a vent chamber and a control chamber. The control chamber is pressurized as liquid rises to the selected level by a standpipe extending downwardly in the tank. The valve closing and opening levels are offset by partly filling the vent chamber with liquid when the main valve is open to hydraulically load the diaphragm. A vacuum breaker valve obstructs backflow through the valve, vents the flow path when the valve is closed, and regulates flow into the vent chamber when the valve is open.